Consumers' growing demand for additional health benefits from the food they consume have changed the food industry over the past decade. The changing lifestyle has led to the search of enrichment of vitamins or pharmaceuticals in food products to provide specific health benefits. The aspiration for greener and cleaner food processing technology has also contributed to the enormous changes.
Crude palm oil (CPO) consists by weight of >90% of triacylglycerols, 2-7% of diacylglycerols, <0.1% of monoacylglycerols, 3-5% of free fatty acids and 1% of minor constituents. These minor constituents include carotenes (500-700 ppm), tocols which include tocopherols, tocotrienols and tocoenol (600-1000 ppm), phytosterols (campesterol, stigmasterol and β-sitosterol) (250-620 ppm), and squalene (200-500 ppm). Thus, this provides a source for the production of a range of palm oil products which may be referred to as specialty palm oil products. Likewise, specialty palm kernel oil products may also be obtained from crude palm kernel oil.
Excess calorie intake has been directly linked to the increase in obesity and coronary heart diseases. This has led to the search for low calorie dietary food or fat substitutes. Research has focused on limiting fat digestion and/or absorption and thus maintaining lower body weight, lower body fat accumulation in a healthy manner and regulating post-meal blood lipids. Diacylglycerols oil has been generally recognized as safe (GRAS) in the United States. It provides 38.9 kJ/g of energy as compared to the 39.6 kJ/g provided by triacylglycerols. The absorption and metabolism of diacylglycerols differs from triacylglycerols thus reducing fat absorption for healthier body. Kao Corporation of Japan introduced diacylglycerols cooking oil that looks and tastes like conventional edible oil. The oil also contains phytosterols. These were disclosed in U.S. Pat. No. 6,495,536, US2002045000 and US2003054082 Patents. One of the processes used to obtain the diacylglycerols oil is by hydrolyzing fats and oils, distilling the hydrolyzation product to produce fatty acids and glycerin and esterifying in the presence of enzyme (Patent EP0990391). Generally, the process involves enzyme catalysed esterification of fatty acids derived from natural fats and oils and either monoacylglycerols or glycerol.
However, partial acylglycerols (monoacylglycerols and diacylglycerols) have been known to cause turbidity and cloudiness in edible oil upon prolonged storage even at room temperature due to crystallization of the acylglycerols. Although the quality of the oil remains the same, consumers perceive otherwise. Thus many processes have been developed to produce low partial acylglycerols oil. These include solvent-solvent partition, interesterification in the presence of catalyst and by the use of additives. However, these processes involved numerous steps and the use of hazardous chemicals in one way or another.
Palm oil is the richest plant source of carotenes with concentration of 500-700 ppm. Carotenes are important anti-oxidant by scavenging free radicals and as singlet oxygen quencher. Carotenes are also found to be capable of inhibiting the growth of certain cancer cells such as the lungs and colon cancers. Major carotenes in palm oil—α- and β-carotenes are pro-vitamin A. Vitamin A is useful in preventing xeropthlamia, a night blindness disease.
Current refining technology for the production of refined palm oil destroys carotenes which is present in CPO. In view of the growing importance of carotenes initiative has been taken to recover them prior to refining. These include the use of adsorbent, resin, saponification, crystallization, solvent extraction and chromatographic methods, etc. However, these processes involve the use of organics solvents and chemicals modification in one way or another and do not produce an edible oil enriched with carotenes.
Amongst the most relevant work for the production of high carotenes palm oil that has been disclosed is a process developed by Malaysian Palm Oil Board (Patent MY 104059A) to retain >90% carotenes in the edible oil. The process produces carotenes with concentration less than 0.12%. The process involves numerous steps including degumming, bleaching and mild deacidification with molecular distillation, a gentle distillation process. Another process for the production of high carotenes is disclosed in U.S. Pat. No. 6,177,114. However, the process described involves subjecting the oil to high temperature of 290° C. which is not cost effective.
In some known processes for the production of carotenes concentrate, the palm oil was first catalytically esterified and/or transesterified and then subjected to distillation. The second step includes saponification and evaporation to obtain carotenes as disclosed in U.S. Pat. No. 5,902,890. In U.S. Pat. No. 5,019,668 and EP0349138 Patents, palm oil was esterified and/or transesterified and mixed with edible oil followed by distillation to produce carotenes. GB2218989 Patent comprises steps of (i) esterification of oil (ii) converting the glycerides into monoesters by transesterification, (iii) adsorbing the non-glyceride constituents onto a selective absorbent and (iv) thereafter desorbing the glyceride constituents from the adsorbent with the use of solvent to recover carotenes, and also tocols and sterols.
Tocopherols are important due to their Vitamin E activity. Tocols are useful in protection against skin damage and aging by ultraviolet (UV) radiation. They also exhibit cholesterol-lowering effect. Tocotrienols (>75% of tocols in CPO) have been found to be more powerful anti-oxidant than tocopherol.
GB Patent 2218989 as discussed also produced tocols from esterified palm oil. High concentration of tocols from palm oil by-products is produced as in Patent MY 110779A by (i) catalytic conversion of free fatty acids and acylglycerols in palm fatty acids distillates into esters, (ii) separating tocols from ester, (iii) concentrating tocols by ion-exchange resin and distillation. Both processes disclosed involve esterifying the palm oil and its by-products prior to adsorption on adsorbent such as activated alumina, activated carbon, or silica and ion exchange resins, respectively. These therefore involve a number of steps and adsorption and/or desorption with usage of solvents.
The isolation of phytosterols and squalene from palm oil are disclosed in GB22 18989 and U.S. Pat. No. 6,586,201. These processes involve the use of adsorbents and solvents.
The soapstock by-product from chemical refining of edible vegetable oils such as soybean provides the cheap and readily available supply of fatty acids. The soapstocks cannot be used directly for end uses because of the presence of oxidized contaminants (e.g. carbonyls and peroxides), neutral oil, salts and large quantities of water. The crude soapstocks have a relatively high level of non-hydrolyzeable phospholipids from degumming, thus are more difficult to acidulate.
The soapstocks acidulation process involves numerous steps and the usage of hazardous chemicals. In view of these, one single step process is sought to produce free fatty acids which can be used for oleochemicals industry.
The present invention overcomes the shortcomings of the prior art by providing a process for the production of vegetable oil products including palm oil products and palm kernel oil products containing one or more constituents from a group which includes monoacylglycerols, diacylglycerols, triacylglycerols, carotenes, tocols, phytosterols, squalene and free fatty acids, which is simple, efficient and free from hazardous solvents and chemical processes.